The present invention relates to a positive working photosensitive composition which is used in the manufacturing process of a semiconductor device such as IC, in the production of a circuit substrate for liquid crystal, a thermal head or the like, and in other photofabrication processes. More particularly, the invention concerns a positive working photosensitive composition suitable for photofabrication processes using far ultraviolet rays of 250 nm or shorter as a light source for exposure.
A generally used positive working photoresist composition comprises an alkali-soluble resin and a naphthoquinonediazide compound as a photosensitive substance. As examples of such a composition, the combinations of novolak-type phenol resins with naphthoquinonediazido-substituted compounds are described in U.S. Pat. No. 3,666,473, 4,115,128 and 4,173,470. Further, as the most typical compositions, the combinations of novolak resins prepared from cresols and formaldehyde with trihydroxybenzophenone-1,2-naphthoquinonediazide sulfonic acid esters are described in L. F. Thompson, Introduction to Microlithography, No. 2, 19, pages 112-121, ACS publisher.
In such a positive photoresist, which is basically constituted of a novolak resin and a quinonediazide compound, the novolak resin acts so as to provide high resistance to plasma etching and the naphthoquinonediazide compound functions as a dissolution inhibitor. Further, the naphthoquinonediazide has a characteristic of generating a carboxylic acid upon irradiation with light to lose the ability to inhibit dissolution, thereby heightening the solubility of the novolak resin in alkali.
From the aforementioned points of view, a large number of positive photoresist compositions comprising novolak resins and photosensitive compounds of naphthoquinonediazide type have hitherto been developed and put to practical use. In the working for reproducing lines having a width of the order of 0.8-2 xcexcm, those compositions have accomplished satisfactory results.
On the other hand, the integration degree of an integrated circuit has become higher and higher in recent years, so that the working for super fine patterns having a line width of half micron or below has come to be required in the production of semiconductor substrates for VLSI and the like.
As a means for elevating the fineness of patterns, it is known to shorten the wavelengths of an exposure light source used for the formation of resist patterns. Such a means can be explained by the Rayleigh equation relating to the resolution (line width) R of an optical system:
R=kxc2x7xcex/NA
wherein xcex is the wavelength of an exposure light source, NA is the aperture number of a lens and k is a process constant. From this equation, it can be understand that the attainment of high resolution, namely the diminution in the value of R, becomes possible by shortening the wavelength (xcex) of an exposure light source.
For instance, up to now i-line (365 nm) of a high-pressure mercury lamp has been used as a light source in the production of DRAM having an integration degree of 64 Mbit or below. In the mass production process of 256 Mbit DRAM, the use of KrF excimer laser (248 nm) instead of i-line as an exposure light source has been studied.
Further, light sources emitting light of shorter wavelengths are under examination with the intention of producing DRAM with an integration degree of 1 Gbit or above, and the utilization of ArF excimer laser (193 nm), F2 excimer laser (157 nm), X-ray, electron beams or the like is considered effective (a book written by Koh Ueno et al., entitled xe2x80x9cPhotoresist Materials Responsive to Radiations of Short Wavelengthsxe2x80x94Microlithography for Production of VLSIxe2x80x9d, published by Bunshin Shuppan, in 1988).
In a case where a conventional resist comprising a novolak resin and a naphthoquinonediazide compound is used for forming patterns by the lithography using far ultraviolet light or an excimer laser beam, it is difficult for the light to reach the lower part of the resist because a novolak resin and naphthoquinonediazide have strong absorption in the far ultraviolet region, so that such a resist has low sensitivity and can merely provide a pattern profile having a tapered shape.
As one means for solving the aforementioned problems, the chemical amplification type resist compositions disclosed, e.g., in U.S. Pat. No. 4,491,628 and European Patent 0,249,139 can be employed. The positive resist compositions of chemical amplification type are pattern forming materials of the type which generate acids in the exposed area by irradiation with an actinic radiation, such as far ultraviolet light, to cause the reaction utilizing these acids as catalyst, thereby making a difference of solubility in a developer between the areas irradiated and unirradiated with the actinic radiation. By virtue of this solubility difference, a pattern can be formed on a substrate coated with a material of the foregoing type.
As examples of such a chemical amplification type resist composition, mention may be made of the combination of a compound capable of generating an acid by photolysis (hereinafter referred to as a photo-acid generator) with acetal or an O, N-acetal compound (JP-A-48-89003, wherein the term xe2x80x9cJP-Axe2x80x9d means an unexamined published Japanese patent applicationxe2x80x9d), the combination of a photo-acid generator with an orthoester or amidoacetal compound (JP-A-51-120714), the combination of a photo-acid generator with a polymer having acetal or ketal groups in its main chain (JP-A-53-133429), the combination of a photo-acid generator with an enol ether compound (JP-A-55-12995), the combination of a photo-acid generator with an N-acyliminocarbonic acid compound (JP-A-55-126236), the combination of a photo-acid generator with a polymer having orthoester groups in its main chain (JP-A-56-17345), the combination of a photo-acid generator with a tertiary alkyl ester compound (JP-A-60-3625), the combination of a photo-acid generator with a silyl ester compound (JP-A-60-10247) and the combinations with a photo-acid generator with silyl ether compounds (JP-A-60-37549 and JP-A-60-121446). Those combinations have a quantum yield greater than 1 in principle, so that they exhibit high sensitivity.
As examples of a similar system to the above, which decomposes upon heating in the presence of an acid to acquire solubility in an alkali, mention may be made of the systems wherein tertiary or secondary carbon-containing (e.g., t-butyl, 2-cyclohexenyl) esters or carbonate compounds are combined with compounds capable of generating acids upon exposure to light, as described, e.g., in JP-A-59-45439, JP-A-60-3625, JP-A-62-229242, JP-A-63-27829, JP-A-63-36240, JP-A-63-250642, JP-A-5-181279, Polym. Eng. Sce., vol. 23, p. 1012 (1983); ACS. Sym., vol. 242, p. 11 (1984); Semiconductor World, the November number, p. 91 (1987); Macromolecules, vol. 21, p. 1475 (1988); and SPIE, vol. 920, p. 42 (1988); the systems wherein the acetal compounds described, e.g., in JP-A-4-219757, JP-A-5-249682 and JP-A-6-65332 are combined with the photo-acid generators as recited above, and the systems wherein the t-butyl ether compounds described, e.g., in JP-A-4-211258 and JP-A-6-65333 are combined with the photo-acid generators as recited above.
Those systems each use as a main component a resin whose basic skeleton is a poly(hydroxystyrene) having a small absorption in the wave length region around 248 nm. When KrF excimer laser is employed as an exposure light source, therefore, they can have high sensitivity and high resolution and form good patterns, namely they can be good systems, compared with a conventional naphthoquinonediazide/novolak resin system.
In cases where light sources emitting light of further short wavelengths, such as ArF excimer laser (193 nm) are used for exposure, even the chemical amplification systems recited above are unsuitable because the compounds having aromatic groups show essentially great absorption in the wave length region around 193 nm. Also, the utilization of poly(meth)acrylate, which shows small absorption in the wave length region around 193 nm, is described in J. Vac. Sci. Technol., B9, 3357 (1991). However, this polymer has a problem of having low resistance to dry etching which is generally carried out in a process of producing semiconductors, compared with conventional phenol resins having aromatic groups.
On the other hand, the fact that alicyclic group-containing polymers have dry etching resistance comparable to those of polymers having an aromatic group and show small absorption in the wave length region around 193 nm was reported in Proc. of SPIE, 1672, 66 (1992), and since then the utilization of those polymers has been examined extensively. Examples of such an alicyclic group-containing polymer include the polymers described in JP-A-4-39665, JP-A-5-80515, JP-A-5-265212, JP-A-5-297591, JP-A-5-346668, JP-A-6-289615, JP-A-6-324494, JP-A-7-49568, JP-A-7-185046, JP-A-7-191463, JP-A-7-199467, JP-A-7-234511, JP-A-7-252324 and JP-A-8-259626.
Further, it is shown in Proc. of SPIE, 1672, 66 (1992) that adamantyl groups have the best dry etching resistance of the alicyclic groups recited in those references, and the polymers having adamantyl groups are described in JP-A-4-39665, JP-A-7-199467, JP-A-7-234511, and JP-A-8-259626.
However, since these polymers are (meth)acrylate polymers, they do not have highly satisfactory dry etching resistance necessarily. Further, in copolymerizing a hydrophobic monomer having an adamantyl group with an acid-decomposable monomer required for image formation and a hydrophilic (polar) monomer required for adhesion to a substrate, those monomers were hard to introduce uniformly into the polymer chain. Accordingly, it occurred sometimes that the ununiform copolymerization resulted in a lowering of the solubility of the copolymer in a solvent or the reproducibility of the synthesis was poor.
An object of the present invention is to provide a positive working photosensitive composition suitable for exposure using a light source of a wavelength of 250 nm or shorter, particularly 220 nm or shorter. More specifically, the present invention aims at providing a positive working photosensitive composition which can afford satisfactory sensitivity and high resolution when a light source of a wavelength of 250 nm or shorter, particularly 220 nm or shorter, is used for exposure, and further exhibits sufficient dry etching resistance and satisfactory solubility in a solvent.
As a result of our intensive studies which have been made taking the aforementioned properties into consideration, it has been found that the above-described object of the present invention can be attained by using a resin which comprises constitutional repeating units having particular alicyclic groups and has acid-decomposable groups, thereby achieving the present invention.
More specifically, the present invention has any of the following constitutions (1) to (15).
The constitution (1) is a positive working photosensitive composition comprising:
(A) a compound which can generate an acid upon irradiation with actinic rays or radiation, and
(B) a resin which comprises as constitutional repeating units at least one adamantyl group-containing unit selected from the units represented by the following formula (Ia), (IIa) or (IIIa), and further has at least groups capable of decomposing due to the action of an acid to increase the solubility of the resin in an alkali developer: 
xe2x80x83wherein R1, R2, R5, R8 and R9, which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a haloalkyl group; R4, R7 and R10, which may be the same or different, each represents a halogen atom, a cyano group, an alkyl group which may have substituent(s), an alkenyl group which may have substituent(s), an alkinyl group which may have substituent(s), or xe2x80x94COxe2x80x94Oxe2x80x94R11; R3, R6 and R11, which may be the same or different, each represents a hydrogen atom, an alkyl group which may have substituent(s), a monocyclic or polycyclic cycloalkyl group which may have substituent(s), an alkenyl group which may have substituent(s), or a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer; X1, X2, X3, X4 and X5, which may be the same or different, each represents a single bond, a divalent alkylene group, a cycloalkylene group, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, or xe2x80x94N(R12)xe2x80x94R13xe2x80x94; R12 represents a hydrogen atom, an alkyl group, a monocyclic or polycyclic cycloalkyl group, or an alkenyl group; R13 represents a single bond, or a divalent alkylene, cycloalkylene or alkenylene group which may have an ether group, an ester group, an amido group, an urethane group or an ureido group; l, m and n, which may be the same or different, each represents 0 or an integer from 1 to 3; and when l is 2 or 3, the R4 groups may be the same or different, when m is 2 or 3, the R7 groups may be the same or different, and when n is 2 or 3, the R10 groups may be the same or different.
The constitution (2) is a positive working photosensitive composition according to the constitution (1), wherein the resin as Component (B) further comprises at least one unit selected from constitutional repeating units represented by the following formula (IVa), (Va) or (VIa); 
wherein R14, R15, R17, R18 and R19, which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a haloalkyl group; R16 represents a cyano group, xe2x80x94COxe2x80x94OR20 or xe2x80x94COxe2x80x94N(R21)(R22); X6, X7 and X8, which may be the same or different, each represents a single bond, xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94Oxe2x80x94CO-R23xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94R24xe2x80x94, xe2x80x94COxe2x80x94N(R25)xe2x80x94R26xe2x80x94, a divalent alkylene which may have substituent(s), a divalent alkenylene which may have substituent(s), or a divalent cycloalkylene group which may have substituent(s); R20 represents a hydrogen atom, or an alkyl, cycloalkyl or alkenyl group which may have substituent(s), or a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer; R21, R22 and R25, which may be the same or different, each represents a hydrogen atom, an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s), or an alkenyl group which may have substituent(s), or R21 and R22 may combine with each other to form a ring; R23, R24 and R26, which may be the same or different, each represents a single bond, or a divalent alkylene, alkenylene or cycloalkylene group which may contain an ether group, an ester group, an amido group, an urethane group or an ureido group; and B represents a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer.
The constitution (3) is a positive working photosensitive composition according to the constitution (1) or (2), wherein the resin as Component (B) further has carboxyl groups.
The constitution (4) is a positive working photosensitive composition according to the constitution (3), wherein the resin as Component (B) contains at least one constitutional repeating unit selected from carboxyl group-containing units of the following formula (VII), (VIII) or (IX): 
wherein R27, R28, R30, R31 and R32, which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a haloalkyl group; R29 represents a cyano group, xe2x80x94COxe2x80x94OR33 or xe2x80x94COxe2x80x94N(R34) (R35); X9, X10 and X11, which may be the same or different, each represents a single bond, xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94R36xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94R37xe2x80x94, xe2x80x94COxe2x80x94N(R38)xe2x80x94R39xe2x80x94, or a divalent alkylene which may have substituent(s), a divalent alkenylene which may have substituent(s), or a divalent cycloalkylene group which may have substituent(s); R33 represents a hydrogen atom, an alkyl group which may have substituent(s), a cycloalkyl which may have substituent(s), or an alkenyl group which may have substituent(s); R34, R35 and R38, which may be the same or different, each represents a hydrogen atom, or an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s), or an alkenyl group which may have substituent(s), or R34 and R35 may combine with each other to form a ring; R36, R37 and R39, which may be the same or different, each represents a single bond, or a divalent alkylene, alkenylene or cycloalkylene group, which may contain an ether group, an ester group, an amido group, an urethane group or an ureido group.
The constitution (5) is a positive working photosensitive composition according to the constitutions (1) to (4), further comprising a low molecular acid-decomposable dissolution inhibiting compound which has a molecular weight of not higher than 3,000, contains a group capable of decomposing due to the action of acids and increases the solubility in an alkali developer when an acid acts thereon.
The constitution (6) is a positive working photosensitive composition of any of the above constitutions (1) to (5), wherein the actinic rays or radiation is far ultraviolet light of wavelengths of 250 nm or shorter.
The constitution (7) is a positive working photosensitive composition according to the constitution (6), wherein the far ultraviolet light has wavelengths of 220 nm or shorter.
The constitution (8) is a positive working photosensitive composition comprising:
(A) a compound capable of generating an acid upon irradiation with an actinic ray or radiation, and
(B) a resin which has at least one of monovalent polycyclic alicyclic groups represented by the following formula (Ib), (IIb) or (IIIb), and has a group capable of decomposing due to the action of acid to increase the solubility of the resin in an alkali developer: 
xe2x80x83wherein R1 to R5, which may be the same or different, each represents an alkyl, cycloalkyl, alkenyl or alkynyl group which may have substituent(s), a halogen atom, a cyano group, a group of formula xe2x80x94R6xe2x80x94Oxe2x80x94R7, a group of formula xe2x80x94R8xe2x80x94COxe2x80x94Oxe2x80x94R9, a group of formula xe2x80x94R10xe2x80x94COxe2x80x94NR11R12, or a group of formula xe2x80x94R13xe2x80x94Oxe2x80x94COxe2x80x94R14; R7 and R9, which may be the same or different, each represents a hydrogen atom, an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s), an alkenyl group which may have substituent(s), or a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer; R11, R12 and R14, which may be the same or different, each represents a hydrogen atom, an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s), an alkenyl group which may have substituent(s), or R11, and R12 may combine with each other to from a ring; R6, R8, R10 and R13, which may be the same or different, each represents a single bond, or an alkylene, alkenylene or cycloalkylene group which may have substituent(s); l, m, n, p and q, which may be the same or different, each represents 0 or an integer of 1 to 5; wherein when l, m, n, p or q is 2 or more, the plural groups represented by each of R1, R2, R3, R4 and R5 may be the same or different, and the combination of two of the groups may represent a carbonyl (xe2x95x90O) or thiocarbonyl (xe2x95x90S) group on one carbon atom, or may complete a double bond between adjacent carbon atoms or a ring; and wherein the bonding hand may be situated at any site of each polycyclic hydrocarbon structure.
The constitution (9) is a positive working photosensitive composition according to the constitution (8), wherein the resin as Component (B) contains at least one of constitutional repeating units represented by the following formula (IVb), (Vb) or (VIb), and has groups capable of decomposing due to the action of an acid to increase the solubility of the resin in an alkali developer: 
wherein R15, R16, R18, R19 and R20, which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a haloalkyl group; R17 represents a cyano group, xe2x80x94COxe2x80x94OR27 or xe2x80x94COxe2x80x94N(R28)(R29); X1, X2 and X3, which may be the same or different, each represents a single bond, a divalent alkylene which may have substituent(s), a divalent alkenylene group which may have substituent(s), a divalent cycloalkylene group which may have substituent(s), xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94R30xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94,R31xe2x80x94, or xe2x80x94COxe2x80x94N(R32)xe2x80x94R33xe2x80x94; R27 represents a hydrogen atom, an alkyl group which may have substituent(s), a cycloalkyl which may have substituent(s), an alkenyl group which may have substituent(s), or a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer; R28, R29 and R32, which may be the same or different, each represents a hydrogen atom, or an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s) or an alkenyl group which may have substituent(s), or R28 and R29 may combine with each other to form a ring; R30, R31 and R33, which may be the same or different, each represents a single bond, or a divalent, alkylene, alkenylene or cycloalkylene group which may form a divalent group in combination with an ether group, an ester group, an amido group, an urethane group or an ureido group; and Y represents a polycyclic aliphatic group represented by formula (Ib), (IIb) or (IIIb).
The constitution (10) is a positive working photosensitive composition according to the constitution (8) or (9), wherein the resin as Component (B) is a resin comprising at least one of constitutional repeating units of formulae (IVb), (Vb) or (VIb) and at least one of constitutional repeating units represented by the following formula (IVa), (Va) or (VIa), and being capable of decomposing due to the action of an acid to increase the solubility in an alkali developer: 
wherein R14, R15, R17, R18 and R19, which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a haloalkyl group; R16 represents a cyano group, xe2x80x94COxe2x80x94OR20 or xe2x80x94COxe2x80x94N(R21)(R22) X6, X7 and X8, which may be the same or different, each represents a single bond, xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94R23xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94R24xe2x80x94, xe2x80x94COxe2x80x94N(R25)xe2x80x94R26xe2x80x94, or a divalent alkylene group which may have substituent(s), a divalent alkenylene group which may have substituent(a), or a divalent cycloalkylene group which may have substituent(s); R20 represents a hydrogen atom, or an alkyl, cycloalkyl or alkenyl group which may have substituent(s), or a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer; R21, R22 and R25. which may be the same or different, each represents a hydrogen atom, or an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s) or an alkenyl group which may have substituent(s), or R21 and R22 may combine with each other to form a ring; R23, R24 and R26, which may be the same or different, each represents a single bond, or a divalent alkylene, alkenylene or cycloalkylene group which may contain an ether group, an ester group, an amido group, an urethane group or an ureido group; and B represents a group which can decompose due to the action of an acid to increase the solubility of the resin in an alkali developer.
The constitution (11) is a positive working photosensitive composition according to any of the constitutions (8) to (10), wherein the resin as Component (B) further has carboxyl groups.
The constitution (12) is a positive working photosensitive composition according to the constitution (11), wherein the resin as Component (B) having the carboxyl groups comprises at least one of the constitutional repeating units selected from carboxyl group-containing units of the following formula (VII), (VIII) or (IX): 
wherein R27, R28, R30, R31 and R32 which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group or a haloalkyl group; R29 represents a cyano group, xe2x80x94COxe2x80x94OR33 or xe2x80x94COxe2x80x94N(R34)(R35); X9, X10 and X11, which may be the same or different, each represents a single bond, xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94R36xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94,R37xe2x80x94, xe2x80x94COxe2x80x94N(R38)xe2x80x94R39xe2x80x94, or a divalent alkylene group which may have substituent(s), a divalent alkenylene group which may have substituent(s), or a divalent cycloalkylene group which may have substituent(s); R33 represents a hydrogen atom, or an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s) or an alkenyl group which may have substituent(s); R34, R35 and R38, which may be the same or different, each represents a hydrogen atom, or an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s) or an alkenyl group which may have substituent(s), or R34 and R35 may combine with each other to form a ring,; R36, R37 and R39, which may be the same or different, each represents a single bond, or a divalent alkylene, alkenylene or cycloalkylene group which may contain an ether group, an ester group, an amido group, an urethane group or an ureido group.
The constitution (13) is a positive working photosensitive composition of any of the constitutions (8) to (12), further comprising a low molecular acid-decomposable dissolution inhibiting compound which has a molecular weight of not higher than 3,000, contains a group capable of decomposing due to the action of acids and increases the solubility in an alkali developer when an acid acts thereon.
The constitution (14) is a positive working photosensitive composition of constitutions (8) to (13), wherein the actinic rays or radiation is far ultraviolet light of wavelengths of 250 nm or shorter.
The constitution (15) is a positive working photosensitive composition according to the constitution (14), wherein the far ultraviolet light has wavelengths of 220 nm or shorter.
The compounds used in the present invention are illustrated below in detail.
In the first place, the resins usable as Component (B) in the present composition are described below.
[1] Constitutional Repeating Units of Formula (Ia), (IIa) or (IIIa)
Examples of an alkyl group for R1, R2, R5, R8 or R9 in the foregoing formulae include an C1-4 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl and sec-butyl. Examples of the haloalkyl group include a C1-4 alkyl group substituted by a fluorine atom, a chlorine atom or a bromine atom, such as fluoromethyl, chloromethyl, bromomethyl, fluoroethyl, chloroethyl and bromoethyl.
Examples of the alkyl group for R4, R7 or R10 include an C1-8 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl, sec-butyl, hexyl, 2-ethylhexyl and octyl. Examples of an alkenyl group include a C2-6 alkenyl group which may have substituent(s), such as vinyl, propenyl, allyl, butenyl, pentenyl, hexenyl and cyclohexenyl. Examples of an alkynyl group include a C2-4 alkynyl group, such as acetyl and propargyl.
Examples of an alkyl group and an alkenyl group for R3, R6, R11, and R12 each include the same groups as recited above with respect to R4, R7 and R10 each. Examples of the monocyclic or polycyclic cycloalkyl group include a C3-8 monocyclic group which may have substituent(s), such as cyclopropyl, cyclopentyl and cyclohexyl, and a polycyclic group which may have substituent(s), such as adamantyl, norbornyl, isobornyl, dicyclopentyl, "sgr"-pinyl and tricyclodecanyl.
Examples of an alkylene group for X1 to X5 include an C1-8 alkylene group which may have substituent(s), such as methylene, ethylene, propylene, butylene, hexylene and octylene. Examples of the cycloalkylene group include a C5-8 cycloalkylene group which may have substituent(s), such as cyclopentylene and cyclohexylene.
Examples of an alkylene group and a cycloalkylene group for R13 include the same groups as recited above with respect to X1 to X5. Examples of an alkenylene group for R13 include a C2-6 alkenylene group, such as ethenylene, propenylene and butenylene. The alkenylene group as R13 can include divalent groups formed by combining the above-described divalent groups (alkylene, cycloalkylene and alkenylene groups) with at least one of an ether, ester, amido, urethane and ureido group.
R3, R6 and R11, each represent a group which can decompose due to the action of an acid to increase the solubility of the resulting resin in an alkali developer (referred to as xe2x80x9can acid-decomposable groupxe2x80x9d, too). For instance, such an acid-decomposable group is a group of the type which is hydrolyzed by acids to produce an acid, or a group of the type which releases a carbon cation due to the action of acids to form an acid. Preferably, the groups as mentioned above are represented by the following formula (X) or (XI): 
wherein R40, R41 and R42, which may be the same or different, each represents a hydrogen atom, an alkyl group which may have substituent(s), a cycloalkyl group which may have substituent(s), or an alkenyl group which may have substituent(s), provided that at least one of R40 to R42 is not a hydrogen atom; R43 represents an alkyl group, a cycloalkyl group or an alkenyl group, which may have substituent(s); or two of R40 to R42 in formula (X) or two of the substituents R40, R41 and R43 in formula (XI) may combine with each other to form a cyclic structure composed of 3 to 8 carbon atoms, which may further contain a hetero atom. Examples of such a cyclic structure include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a 1-cyclohexenyl group, a 2-tetrahydrofuranyl group and a 2-tetrahydropyranyl group; and Z1 and Z2 each represent O or S. The alkyl, cycloalkyl and alkenyl groups for R40 to R43 are the same groups as recited above with respect to R3, R6, R11, and R12 each.
l, m and n each represent 0 or an integer of 1 to 3, preferably 0, 1 or 2.
Examples of the substituent which the foregoing groups each may have include a hydroxyl group, a halogen atom (fluorine, chlorine, bromine or iodine), a nitro group, a cyano group, an amido group, a sulfonamido group, an alkyl group as represented by R3, R6, R11, or R12, an C1-8 alkoxy group such as methoxy, ethoxy, hydroxyethoxy, propoxyt hydroxypropoxy or butoxy, an alkoxycarbonyl group such as methoxycarbonyl or ethoxycarbonyl group, an acyl group such as formyl, acetyl or benzoyl, an acyloxy group such as acetoxy or butyryloxy, and a carboxyl group. Examples of constitutional repeating units represented by formula (Ia), (IIa) and (IIIa) respectively are illustrated below, but these examples should not be construed as limiting the scope of the invention. 
The proportion of alicyclic group-containing constitutional repeating units represented by the foregoing formula (Ia), (IIa) or (IIIa) in the resin according to the present invention, although controlled so as to balance dry etching resistance with alkali developability and so on, is preferably at least 20% by mole, more preferably from 30 to 100% by mole, more preferably from 40 to 90% by mole, most preferably from 45 to 75% by mole, to the total repeating units.
[2] Constitutional Repeating Units having Acid-Decomposable Groups
As for the resins relating to the present invention, the acid-decomposable groups may be present in constitutional repeating units of formula (Ia), (IIa) or (IIIa) (as R3, R6 or R11), or/and other constitutional repeating units.
Preferably, the constitutional repeating units having acid-decomposable groups are units of formula (IVa), (Va) or (VIa).
Examples of an alkyl group for R14, R15, R17, R18 or R19 in the foregoing formulae (IVa) to (VIa) include an C1-4 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl and sec-butyl. Examples of the haloalkyl group include an C1-4 alkyl group substituted by a fluorine atom, a chlorine atom or a bromine atom, such as fluoromethyl, chloromethyl, bromomethyl, fluoroethyl, chloroethyl and bromoethyl.
Examples of the alkyl group for R20, R21, R22 or R25 include an C1-8 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl, sec-butyl, hexyl, 2-ethylhexyl and octyl. Examples of the cycloalkyl group include a C3-8 cycloalkyl group which may have substituent(s), such as cyclopropyl, cyclopentyl and cyclohexyl. Examples of the alkenyl group include a C2-6 alkenyl group which may have substituent(s), such as vinyl, propenyl, allyl, butenyl, pentenyl, hexenyl and cyclohexenyl groups. Examples of the nitrogen-containing ring completed by combining R21 and R22 include 5- to 8-membered rings, such as pyrrolidine, piperidine and piperazine rings.
Examples of the alkylene group for X6 to X8, R23, R24 or R26 include an C1-8 alkylene group which may have substituent(s), such as methylene, ethylene, propylene, butylene, hexylene and octylene. Examples of the alkenylene group include a C2-6 alkenylene group which. may have substituent(s), such as ethenylene, propenylene and butenylene. Examples of the cycloalkylene group include a C5-8 cycloalkylene group which may have substituent(s), such as cyclopentylene and cyclohexylene. R23, R24 or R26 may be a divalent group formed by combining an alkylene, alkenylene or cycloalkylene group as recited above with at least one of ether, ester, amido, urethane and ureido groups.
Examples of the substituent which the aforementioned groups may have include a hydroxyl group, a halogen atom (fluorine, chlorine, bromine or iodine), a nitro group, a cyano group, an amido group, a sulfonamido group, an alkyl group as represented by R20, R21, R22 or R25, an C1-8 alkoxy group such as methoxy, ethoxy, hydroxyethoxy, propoxy, hydroxypropoxy or butoxy, an alkoxycarbonyl group such as methoxycarbonyl or ethoxycarbonyl, an acyl group such as formyl, acetyl or benzoyl, an acyloxy group such as acetoxy or butyryloxy, and a carboxyl group.
B and R20 each represent a group capable of decomposing due to the action of acids to increase the solubility of the resulting resin in an alkali developer. Examples of such an acid-decomposable group include a group of the type which is hydrolyzed by the action of acids to produce an acid, and a group of the type which releases a carbon cation due to the action of acids to form an acid. As groups of those types, the groups of formula (X) or (XI) illustrated with respect to R3, R6 and R11 are preferred.
Examples of constitutional repeating units represented by formula (IVa), (Va) and (VIa) respectively are illustrated below, but these examples should not be construed as limiting the scope of the invention. 
The proportion of the acid decomposable group-containing constitutional repeating units (preferably, those represented by the foregoing formula (IVa), (Va) or (VIa)) in the resin according to the present invention is preferably from 0 to 50% by mole, more preferably from 5 to 40% by mole, most preferably from 10 to 30% by mole, to the total repeating units, although controlled depending on the properties to be achieved including alkali developability, adhesion to a substrate and dry etching resistance. This proportion is the total proportion of all the acid decomposable group-containing constitutional repeating units in the resin including the proportion of constitutional repeating units which are represented by formula (Ia), (IIa) or (IIIa) and have acid-decomposable groups.
Other resins usable as the Component (B) of the present invention, wherein polycyclic alicyclic groups of formula (Ib), (IIb) or (IIIb) and acid-decomposable groups are present, are illustrated below in detail.
The polycyclic alicyclic groups of formula (Ib), (IIb) or (IIIb) and acid-decomposable groups can be attached to any sites in the mother resin. Namely, the polycyclic alicyclic group of formula (Ib), (IIb) or (IIIb) and an acid-decomposable group may be attached to different repeating units of the resin, or those groups may be attached to the same repeating unit. Further, the resin may be composed of the mixture of these types.
The repeating units having groups represented by formula (Ib), (IIb) or (IIIb) which are incorporated into the resin are preferably constitutional repeating units represented by formula (IVb), (Vb) or (VIb).
Examples of an alkyl group for R1 to R5, R7, R9, R11, R12, R14, R27 to R29, or R32 in the foregoing formula (IVb), (Vb) or (VIb) include an C1-8 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl, sec-butyl, hexyl, 2-ethylhexyl and octyl. Examples of the cycloalkyl group include a C3-8 cycloalkyl group which may have substituent(s), such as cyclopropyl, cyclopentyl and cyclohexyl, and examples of the alkenyl group include a C2-6 alkenyl group which may have substituent(s), such as vinyl, propenyl, allyl, butenyl, pentenyl, hexenyl and cyclohexenyl. Examples of the alkynyl group for R1 to R5 include a C2-4 alkynyl group such as acetyl and propargyl.
Therein, when l, m, n, p or q is 2 or more, the two or more of each of R1, R2, R3, R4 and R5 may be the same or different, and when the two groups are attached to the same carbon atom, they may represent a carbonyl group (xe2x95x90O) or a thiocarbonyl group (xe2x95x90S) together. (Namely, a carbonyl group or a thiocarbonyl group may be bonded to the carbon atom on each ring, and such a case can be regarded as the case where two of each of R1 to R5 are bonded to the same carbon atom.)
When two of the Ri groups (i=1 to 5) are attached to adjacent carbon atoms, on the other hand, they may combine with each other to complete a Cxe2x80x94C double bond. However, it is undesirable that the thus formed Cxe2x80x94C double bonds make a conjugate Cxe2x80x94C double bond system.
Further, when l, m, n, p and q each are two or more, two groups among the groups represented by R1 to R5 may combine to form a ring when they are adjacent to each other. Examples of such a ring include 3- to 8-membered rings which may contain a hetero atom, such as cyclopropane, cyclopentane, cyclohexane, cycloheptane, tetrahyrofuran and tetrahydropyran. These rings may further have substituent(s).
The bonding hand of the monovalent polycyclic alicyclic group represented by formula (Ib), (IIb) or (IIIb) may be situated at any site of each polycyclic hydrocarbon structure.
Examples of the alkyl group for R15, R16, R18 to R22, and R24 to R26 include an C1-4 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl and sec-butyl. Examples of the haloalkyl group include an C1-4 alkyl group substituted by a fluorine atom, a chlorine atom or a bromine atom, such as fluoromethyl, chloromethyl, bromomethyl, fluoroethyl, chloroethyl and bromoethyl.
Examples of the alkylene group for R6, R8, R10, R13 and X1 to X6 include an C1-8 alkylene group, such as methylene, ethylene, propylene, butylene, hexylene and octylene, which may have substituent(s). Examples of the alkenylene group include a C2-6 alkenylene group which may have substituent(s), such as ethenylene, propenylene and butenylene. Examples of the cycloalkylene group include a C5-8 cycloalkylene group which may have substituent(s), such as cyclopentylene and cyclohexylene.
Examples of the alkylene group, alkenylene and cycloalkylene group for R30, R31 and R33 include the same groups as recited above. R30, R31 and R33 can include divalent groups formed by combining these divalent groups with at least one of an ether, ester, amido, urethane and ureido group.
Examples of the nitrogen-containing ring formed by combining R11 with R12, or by combining R28 with R29 include 5- to 8-membered rings, such as pyrrolidine, piperidine and piperazine.
R7, R9, R27 and B each represent a group which can decompose due to the action of acids to increase the solubility of the resulting resin in an alkali developer (an acid-decomposable group).
As for the resins relating to the present invention, the acid-decomposable groups may be present as R7 or R9 in the structures of groups represented by formula (Ib), (IIb) or (IIIb), or as R27 in constitutional repeating units having groups represented by formula (Ib), (IIb) or (IIIb), or in other constitutional repeating units. Further, they may be situated at two or more of those different types of positions.
Examples of an acid-decomposable group include a group of the type which is hydrolyzed by acids to produce an acid, or a group of the type which releases a carbon cation due to the action of acids to form an acid. Preferred examples thereof include those represented by the following formula (XIII) or (XIV). By virtue of these groups, the aging stability is enhanced. 
wherein R47, R48 and R49, which may be the same or different, each represents a hydrogen atom, or an alkyl, cycloalkyl or alkenyl group which may have substituent(s), provided that at least one of R47 to R49 is not a hydrogen atom; R50 represents an alkyl group, a cycloalkyl group or an alkenyl group, which may have substituent(s); or two of R47 to R49 in formula (XIII) or two of R47, R48 and R50 in formula (XIV) may combine with each other to form a cyclic structure constituted of 3 to 8 carbon atoms, which may further contain a hetero atom. Examples of such a cyclic structure includes a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a 1-cyclohexenyl group, a 2-tetrahydrofuranyl group and a 2-tetrahydropyranyl group. Z1 and Z2, which may be the same or different, each represent an oxygen atom or a sulfur atom.
The alkyl, cycloalkyl and alkenyl groups for R47 to R50 include the same groups as recited above with respect to R1 to R5.
l, m, n, p and q each represent 0 or an integer of 1 to 5, preferably 0, 1 or 2.
Examples of the substituent which the foregoing groups may have include a hydroxyl group, a halogen atom (fluorine, chlorine, bromine or iodine), a nitro group, a cyano group, an amido group, a sulfonamido group, an alkyl group as represented by R1 to R5, an alkoxy group such as methoxy, ethoxy, hydroxyethoxy, propoxy, hydroxypropoxy or butoxy, an alkoxycarbonyl group such as methoxycarbonyl or ethoxycarbonyl, an acyl group such as formyl, acetyl or benzoyl, an acyloxy group such as acetoxy or butyryloxy, and a carboxyl group.
The proportion of constitutional repeating units having alicyclic groups represented by the foregoing formula (Ib), (IIb) or (IIIb) (preferably, constitutional repeating units of formula (IVb) to (VIb)) in the resin according to the present invention is preferably at least 20% by mole, more preferably from 30 to 80% by mole, most preferably from 40 to 65% by mole, to the total repeating units, although controlled so as to balance dry etching resistance with alkali developability and so on.
The proportion of constitutional repeating units having the aforementioned acid-decomposable groups (preferably, those represented by the foregoing formula (IVa), (Va) or (VIa)) in the resin according to the present invention is preferably from 5 to 80% by mole, more preferably from 10 to 70% by mole, most preferably from 20 to 60% by mole, to the total repeating units, although controlled depending on the properties to be achieved including alkali developability, adhesion to a substrate and so on. This proportion is the total proportion of all the acid decomposable group-containing constitutional repeating units in the resin including those contained in the constitutional repeating units having groups represented by formula (Ib), (IIb) or (IIIb).
Examples of constitutional repeating units represented by the foregoing formulae (IVb), (Vb) and (VIb) respectively, from (axe2x80x21) to (axe2x80x233), are illustrated below, but these examples should not be construed as limiting the scope of the present invention in any way. 
[3] Constitutional Repeating Units having Carboxyl Groups
In the resin to be used in the present invention, the carboxyl group may be present in constitutional repeating units of the foregoing formula (Ia), (IIa) or (IIIa), constitutional repeating units having groups of the foregoing formula (Ib), (IIb) or (IIIb), constitutional repeating units having acid-decomposable groups, or other constitutional repeating units. Further, the carboxyl groups may be situated at two or more of the different types of positions recited above.
Preferably, the constitutional repeating units having carboxyl groups are repeating units of the foregoing formula (VII), (VIII) or (IX).
Examples of an alkyl group for R27, R28, R30 to R32 in formula (VII) to (IX) include an C1-4 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl and sec-butyl. Examples of the haloalkyl group for R27, R28, R30 to R32 include an C1-4 alkyl group substituted with a fluorine, chlorine or bromine atom, such as fluoromethyl, chloromethyl, bromomethyl, fluoroethyl, chloroethyl and bromoethyl.
Examples of an alkyl group for R34, R35 or R38 include an C1-8 alkyl group which may have substituent(s), such as methyl, ethyl, propyl, n-butyl, sec-butyl, hexyl, 2-ethylhexyl and octyl. Examples of the cycloalkyl group include a C3-8 cycloalkyl group, such as cyclopropyl, cyclopentyl and cyclohexyl, which may have substituent(s). Examples of the alkenyl group include a C2-6 alkenyl group which may have substituent(s), such as vinyl, propenyl, allyl, butenyl, pentenyl, hexenyl and cyclohexenyl. Examples of the nitrogen-containing ring formed by combining R34 and R35 include 5- to 8-membered rings, such as pyrrolidine, piperidine and piperazine.
Examples of the alkylene group for X9 to X11, R36, R37 or R39 include an C1-8 alkylene group which may have substituent(s), such as methylene, ethylene, propylene, butylene, hexylene and octylene. Examples of the alkenylene group include a C2-6 alkenylene group which may have substituent(s), such as ethenylene, propenylene and butenylene. Examples of the cycloalkylene group include a C5-8 cycloalkylene group which may have substituent(s), such as cyclopentylene and cyclohexylene. R36, R37 or R39 may be a divalent group formed by combining an alkylene, alkenylene or cycloalkylene group as recited above with at least one selected from ether, ester, amido, urethane and ureido groups.
Examples of the substituent which the aforementioned groups may have include a hydroxyl group, a halogen atom (fluorine, chlorine, bromine or iodine), a nitro group, a cyano group, an amido group, a sulfonamido group, an alkyl group as represented by R34, R35 or R38, a C1-8 alkoxy group such as methoxy, ethoxy, hydroxyethoxy, propoxy, hydroxypropoxy or butoxy, an alkoxycarbonyl group such as methoxycarbonyl or ethoxycarbonyl, an acyl group such as formyl, acetyl or benzoyl, an acyloxy group such as acetoxy or butyryloxy, and a carboxyl group.
Examples of constitutional repeating units represented by formulae (VII), (VIII) and (IX) are illustrated below, but these examples should not be construed as limiting the scope of the invention in any way. 
The proportion of the carboxyl group-containing constitutional repeating units (preferably, those represented by the foregoing formula (VII), (VIII) or (IX)) in the resin according to the present invention is preferably from 0 to 60% by mole, more preferably from 0 to 40% by mole, most preferably from 0 to 20% by mole, to the total constitutional repeating units, although controlled depending on the properties to be achieved, including alkali developability, adhesion to a substrate and sensitivity. This proportion is the total proportion of all the carboxyl group-containing constitutional repeating units in the resin, including the proportion of constitutional repeating units represented by formula (Ia), (IIa) or (IIIa) and constitutional repeating units which have not only carboxyl groups but also acid-decomposable groups.
[4] Resins as Component (B) Which Have the Above-Described Constitutional Repeating Units
For the purpose of enhancing the properties of the resin as Component (B) of the present invention, other polymerizable monomers may be copolymerized so far as they do not significantly impair the transmittance of the resulting resin at wavelengths of 220 nm or shorter and the dry etching resistance. The copolymerizable monomers which can be used for the aforesaid purpose are as in the following. Examples of the copolymerizable monomers include compounds having one addition polymerizable unsaturated bond per molecule, which are selected from acrylic acid esters, acrylic amides, methacrylic acid esters, methacrylic amides, allyl compounds, vinyl ethers, vinyl esters, styrenes, or crotonic acid esters.
More specifically, those compounds include acrylic acid esters, such as alkyl acrylates wherein the alkyl group preferably has 1 to 10 carbon atoms (e.g., methyl acrylate, ethyl acrylate, propyl acrylate, t-butyl acrylate, amyl acrylate, cyclohexyl acrylate, ethylhexyl acrylate, octyl acrylate, t-octyl acrylate, chloroethyl acrylate, 2-hydroxyethyl acrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, glycidyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate) and aryl acrylates (e.g., phenyl acrylate, hydroxyphenyl acrylate); methacrylic acid esters, such as alkyl methacrylates wherein the alkyl group preferably has 1 to 10 carbon atoms (e.g., methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, t-butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, glycidyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate) and aryl methacrylates (e.g., phenyl methacrylate, hydroxyphenyl methacrylate, cresyl methacrylate, naphthyl methacrylate); acrylic amides, such as acrylic amide, N-alkylacrylic amides (the alkyl moeity preferably having 1 to carbon atoms, such as methyl, ethyl, propyl, butyl, t-butyl, heptyl, octyl, cyclohexyl, benzyl, hydroxyethyl and benzyl), N-arylacrylic amides (the aryl moeity being preferably phenyl, tolyl, nitrophenyl, naphthyl, cyanophenyl, hydroxyphenyl and carboxyphenyl), N,N-dialkylacrylic amides (the alkyl moeity preferably having 1 to 10 carbon atoms, such as methyl, ethyl, butyl, isobutyl, ethylhexyl and cyclohexyl), N,N-arylacrylic amides (the aryl moeity being preferably a phenyl group), N-methyl-N-phenylacrylic amide, N-hydroxyethyl-N-methylacrylic amide and N-2-acetamidoethyl-N-acetylacrylic amide; methacrylic amides, such as methacrylic amide, N-alkylmethacrylic amides (the alkyl moeity preferably having 1 to 10 carbon atoms, such as methyl, ethyl, t-butyl, ethylhexyl, hydroxyethyl and cyclohexyl), N-arylmethacrylic amides (the aryl moeity being preferably phenyl, hydroxyphenyl and carboxyphenyl), N,N-dialkylmethacrylic amides (the alkyl moeity being preferably ethyl, propyl and butyl), N,N-diarylmethacrylic amides (the aryl moeity being preferably a phenyl group), N-hydroxyethyl-N-methylmethacrylic amide, N-methyl-N-phenylmethacrylic amide and N-ethyl-N-phenylmethacrylic amide; allyl compounds, such as allyl esters (e.g., allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate) and allyl oxyethanol; vinyl ethers, such as alkyl vinyl ethers (e.g., hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, butylamihoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether) and vinyl aryl ethers (e.g., vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4-dichlorophenyl ether, vinyl naphthyl ether, vinyl anthranyl ether); vinyl esters, such as vinyl butyrate, vinyl isobutyrate, vinyl trimethylacetate, vinyl diethylacetate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxyacetate, vinyl phenylacetate, vinyl acetoacetate, vinyl lactate, vinyl-p-phenyl butyrate, vinyl cyclohexylcarboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate and vinyl naphthoate; styrenes, such as styrene, alkylstyrenes (e.g., methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene), alkoxystyrenes (e.g., methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene), halogenostyrenes (e.g., chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene), hydroxystyrenes (e.g., 4-hydroxystyrene, 3-hydroxystyrene, 2-hydroxystyrene, 4-hydroxy-3-methylstyrene, 4-hydroxy-3,5-dimethylstyrene, 4-hydroxy-3-methoxystyrene, 4-hydroxy-3-(2-hydroxybenzyl)styrene) and carboxystyrene; crotonic acid esters, such as alkyl crotonates (e.g., butyl crotonate, hexyl crotonate, glycerine monocrotonate); dialkyl itaconates (e.g., dimethyl itaconate, diethyl itaconate, dibutyl itaconate); dialkyl esters of maleic acid or fumaric acid (e.g., dimethyl maleate, dibutyl fumarate); maleic anhydride; maleimide; acrylonitrile; methacrylonitrile; and maleylonitrile. In addition, other addition polymerizable unsaturated compounds, which are generally copolymerizable, may be included.
Of those compounds, the monomers which can increase the solubility in an alkali are preferable, and examples thereof include a carboxyl group-containing monomer such as carboxystyrene, N-(carboxyphenyl)acrylic amide and N-(carboxyphenyl)methacrylic amide, a phenolic hydroxyl group-containing monomer such as hydroxystyrene, N-(hydroxyphenyl)acrylic amide, N-(hydroxyphenyl)methacrylic amide, hydroxyphenyl acrylate and hydroxyphenyl methacrylate, and maleimide.
The proportion of those copolymerizable monomers in the resin of the present invention is preferably 50% by mole or below, more preferably 30% by mole or below, to the total constitutional repeating units.
The resin as Component (B) of the present invention wherein the constitutional repeating units of formula (Ia), (IIa) or (IIIa) are present (and the constitutional repeating units of formula (IVa), (Va) or (VIa) and the constitutional repeating units of formula (VII), (VIII) or (IX) may further be present), or the resin as Component (B) of the present invention wherein are present the constitutional repeating units having the groups of formula (Ib), (IIb) or (IIIb) (preferably, the constitutional repeating units of formula (IVb), (Vb) or (VIb)), acid decomposable group-containing constitutional repeating units (preferably, the constitutional repeating units of formula (IVa), (Va) or (VIa)) and, if desired, carboxyl group-containing constitutional repeating units (preferably, the constitutional repeating units of formula (VII), (VIII) or (IX)) and other polymerizable monomers can be synthesized by radical, cationic or anionic polymerization of unsaturated monomers having the structures corresponding to the aforesaid constitutional repeating units.
In more detail, the constituent monomers are mixed on the basis of the preferable composition as mentioned above and dissolved in an appropriate solvent so as to have a monomer concentration of about 10-40% by weight, and the polymerization thereof is carried out by adding thereto a polymerization catalyst and, if necessary, with heating.
The weight average molecular weight (Mw) of the resin as Component (B) of the present invention is at least 2,000, preferably from 3,000 to 1,000,000, more preferably from 5,000 to 200,000, most preferably from 20,000 to 100,000, on a polystyrene basis. The higher the molecular weight of the resin is, the better the heat resistance becomes but the lower the developability becomes. Therefore, the resin is controlled so as to have a molecular weight in a desirable range for keeping an adequate balance between those properties. The dispersion degree (Mw/Mn) is preferably from 1.0 to 5.0, and more preferably from 1.0 to 3.0. The smaller the dispersion degree, the better the heat resistance and the image quality (including a pattern profile and a defocus latitude).
The proportion of the foregoing resin in the photosensitive composition according to the present invention is generally from 50 to 99.7% by weight, preferably from 70 to 99% by weight, to the total solids.
[5] Photo-acid Generators as Component (A)
The photo-acid generator which can be used in the present invention is a compound capable of generating an acid upon irradiation with actinic rays or radiations.
The compounds which can decompose to generate acids when irradiated with actinic rays or radiations can be selected properly from photoinitiators for photo cationic polymerization, photoinitiators for photo radical polymerization, photodecolorizers for dyes, photo discoloring agents, compounds known to generate acids upon irradiation with light (ultraviolet rays having wavelengths of 400 to 200 nm, and far ultraviolet rays, particularly preferably g-line, h-line, i-line and KrF excimer laser beam), ArF excimer laser beam, electron beam, X-ray, molecular beam or ion beam, which are used for microresist, or mixtures of two or more of those agents.
More specifically, the photo-acid generators usable in the present invention include the diazonium salts described, e.g., in S. I. Schlesinger, Photogr. Sci. Eng., 18, 387 (1974), and T. S. Bal et al., Polymer, 21, 423 (1980); onium salts, such as the ammonium salts described, e.g., in U.S. Pat. Nos. 4,069,055, 4,069,056 and Re 27,992, and Japanese Patent Application No. 03-140140, the phosphonium salts described, e.g., in D. C. Necker et al., Macromolecules, 17, 2468 (1984), C. S. Wen et al., Teh. Proc. Conf. Rad. Curing ASIA, p. 478, Tokyo (Oct., 1988), and U.S. Pat. No. 4,069,055 and 4,069,056, the iodonium salts described, e.g., in J. V. Crivello et al., Macromolecules, 10(6), 1307 (1977), Chem. and Eng. News, Nov. 28, p. 31 (1988), European Patent 0,104,143, U.S. Pat. No. 339,049 and 410,210, JP-A-2-150848 and JP-A-2-296514, the sulfonium salts described, e.g., in J. V. Crivello et al., Polymer J., 17, 73 (1985), J. V. Crivello et al., J. Org. Chem., 43, 3055 (1978), W. R. Watt et al., J. Polymer Sci., Polymer Chem. Ed., 22, 1789 (1984), J. V. Crivello et al., Polymer Bull., 14, 279 (1985), J. V. Crivello et al., Macromolecules, 14(5), 1141 (1981), J. V. Crivello et al., J. Polymer Sci., Polymer Chem. Ed., 17, 2877 (1979), European Patents Nos. 0,370,693, 3,902,114, 0,233,567, 0,297,443 and 0,297,422, U.S. Pat. Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013, 4,734,444 and 2,833,827, and German Patents 2,904,626, 3,604,580 and 3,604,581, JP-A-7-28237 and JP-A-8-27102, the selenonium salts described, e.g., in J. V. Crivello et al., Macromolecules, 10(6), 1307 (1977), and J. V. Crivello et al., J. Polymer Sci., Polymer Chem. Ed., 17, 1047 (1979), and the arsonium salts described, e.g., in C. S. Wen et al., Teh. Proc. Conf. Rad. Curing ASIA, p. 478, Tokyo (Oct., 1988); the organic halogeno-compounds described, e.g., in U.S. Pat. No. 3,905,815, JP-B-46-4605 (The term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d), JP-A-48-36281, JP-A-55-32070, JP-A-60-239736, JP-A-61-169835, JP-A-61-169837, JP-A-62-5-8241, JP-A-62-212401, JP-A-63-70243 and JP-A-63-298339; the organometallic compounds/organic halides described, e.g., in K. Meier et al., J. Rad. Curing, 13(4), 26 (1986), T. P. Gill et al., Inorg. Chem., 19, 3007 (1980), D. Astruc, Acc. Chem. Res., 19(12), 377 (1896), and JP-A-2-161445; the photo-acid generators having o-nitrobenzyl type protective groups described, e.g., in S. Hayase et al., J. Polymer Sci., 25, 753 (1987), E. Reichmanis et al., J. Polymer Sci., Polymer Chem. Ed., 23, 1 (1985), Q. Q. Zhu et al., J. Photochem., 36, 85, 39, 317 (1987), B. Amit et al., Tetrahedron Lett., (24) 2205 (1973), D. H. R. Barton et al., J. Chem. Soc., 3571 (1965), P. M. Collins et al., J. Chem. Soc., Perkin I, 1695 (1975), M. Rudinstein et al., Tetrahedron Lett., (17), 1445 (1975), J. W. Walker et al., J. Am. Chem. Soc., 110, 7170 (1988), S. C. Busman et al., J. Imaging Technol., 11(4), 191 (1985), H. M. Houlihan et al., Macromolecules, 21, 2001 (1988), P. M. Collins et al., J. Chem. Soc., Chem. Commun., 532 (1972), S. Hayase et al., Macromolecules, 18, 1799 (1985), E. Reichmanis et al., J. Electrochem. Soc., Solid State Sci. Technol., 130(6), F. M. Houlihan et al., Macromolecules, 21, 2001 (1988), European Patents 0,290,750, 0,046,083, 0,156,535, 0,271,851 and 0,388,343, U.S. Pat. Nos. 3,901,710 and 4,181,531, JP-A-60-198538 and JP-A-53-133022; the compounds generating sulfonic acids by photolysis, the representatives of which are iminosulfonates and so on, as described, e.g., in M. Tunooka et al., Polymer Preprints Japan, 35(8), G. Berner et al., J. Rad. Curing, 13(4), W. J. Mijs et al., Coating Technol., 55(697), 45(1983), Akzo, H. Adachi et al., Polymer Preprints Japan, 37(3), European Patents 0,199,672, 0,084,515, 0,044,115 and 0,101,122, U.S. Pat. Nos. 618,564, 4,371,605 and 4,431,774, JP-A-64-18143, JP-A-2-245756 and Japanese Patent Application No. 3-140109: the disulfone compounds described, e.g., in JP-A-61-166544 and JP-A-2-71270; and the diazoketosulfone and diazodisulfone compounds described, e.g., in JP-A-3-103854, JP-A-3-103856 and JP-A-4-210960.
In addition, the polymers having the main chain or side chains into which those photo-acid-generating groups or compounds are introduced, such as the compounds described, e.g., in X. E. Woodhouse et al., J. Am. Chem. Soc., 104, 5586 (1982), S. P. Pappas et al., J. Imacing Sci., 30(5), 218 (1986), S. Kondo et al., Makromol. Chem., Rapid Commun., 9, 625 (1988), Y. Yamada et al., Makromol. Chem., 152, 153, 163 (1972), J. V. Crivello et al., J. Polymer Sci., Polymer Chem. Ed., 17, 3845 (1979), U.S. Pat. No. 3,849,137, German Patent 3,914,407, JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038, JP-A-63-163452, JP-A-62-153853 and JP-A-63-146029, can be employed.
Further, the compounds capable of generating acids under light described, e.g., in V. N. R. Pillai, Synthesis, (1), 1 (1980), A. Abad et al., Tetrahedron Lett., (47) 4555 (1971), D. H. R. Barton et al., J. Chem. Soc., (C), 329 (1970), U.S. Pat. No. 3,779,778 and European Patent 0,126,712, can also be employed.
Of the above-recited compounds which can decompose upon irradiation with actinic rays or radiation to generate acids, the compounds described below in detail are used to particular advantage.
(1) A trihalomethyl-substituted oxazole compound of the following formula (PAG1), or a trihalomethyl-substituted s-triazine compound of the following formula (PAG2): 
wherein R201 is a substituted or unsubstituted aryl or alkenyl group; R202 is a substituted or unsubstituted aryl, alkenyl or alkyl group, or xe2x80x94C(Y)3; and Y is a chlorine or bromine atom.
Examples of such compounds are illustrated below, but these examples should not be construed as limiting the scope of the present invention. 
(2) An iodonium salt of the following formula (PAG3), or a sulfonium salt of the following formula (PAG4): 
In the above formulae, Ar1 and Ar2 each independently represents a substituted or unsubstituted aryl group. Preferred substituents include alkyl groups, haloalkyl groups, cycloalkyl groups, aryl groups, alkoxy groups, nitro, carboxyl, alkoxycarbonyl groups, hydroxy, mercapto, and halogen atoms.
R203, R204, and R205 each independently represents a substituted or unsubstituted alkyl or aryl group, and preferably represents an aryl group having 6 to 14 carbon atoms, an alkyl group having 1 to 8 carbon atoms, or a substitution derivative thereof. Preferred substituents for the aryl group include alkoxy groups having 1 to 8 carbon atoms, alkyl groups having 1 to 8 carbon atoms, cycloalkyl groups, nitro, carboxyl, mercapto, hydroxy, and halogen atoms. Preferred substituents for the alkyl group include alkoxy groups having 1 to 8 carbon atoms, carboxyl, and alkoxycarbonyl groups.
Zxe2x88x92 represents a counter anion. Examples thereof include perfluoroalkanesulfonate anions, e.g., BF4xe2x88x92, AsF6xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, SiF62xe2x88x92, ClO4xe2x88x92, and CF3SO3xe2x88x92, a pentafluorobenzenesulfonate anion, fused-ring aromatic sulfonate anions, e.g., a naphthalene-1-sulfonate anion, an anthraquinonesulfonate anion, and dyes containing a sulfonate group. However, the counter anion should not be construed as being limited to these examples.
Two of R203, R204, and R205 may be bonded to each other through a single bond or substituent thereof. Ar1 and Ar2 may be bonded to each other likewise.
Specific examples thereof are given below, but the compounds represented by general formula (PAG3) or (PAG4) should not be construed as being limited thereto. 
The above-illustrated onium salts of formulae (PAG3) and (PAG4) are known compounds, and can be prepared using the methods described, e.g., in J. W. Knapczyk et al., J. Am. Chem. Soc., 91, 145 (1969), A. L. Maycok et al., J. Org. Chem., 35, 2532 (1970), E. Goethas et al., Bull. Soc. Chem. Belg., 73, 546 (1964), H. M. Leicester, J. Ame. Chem. Soc., 51, 3587 (1929), J. V. Crivello et al., J. Polym. Chem. Ed., 18, 2677 (1980), U.S. Pat. Nos. 2,807,648 and 4,247,473, and JP-A-53-101331.
(3) A disulfone compound of the following formula (PAG5) or an iminosulfonate compound of the following formula (PAG6):
Ar3xe2x80x94SO2xe2x80x94SO2xe2x80x94Ar4xe2x80x83xe2x80x83(PAG 5)

In the above formulae, Ar3 and Ar4 are each a substituted or unsubstituted aryl group; R206 is a substituted or unsubstituted alkyl or aryl group; and A is a substituted or unsubstituted alkylene, alkenylene or arylene group.
Examples of such compounds are illustrated below, but these examples should not be construed as limiting the scope of the present invention. 
Those compounds which can decompose upon irradiation with actinic rays or radiation to generate acids (photo-acid generators) are used in a proportion of generally from 0.001 to 40% by weight, preferably from 0.01 to 20% by weight, more preferably from 0.1 to 5% by weight, to the total weight of the photosensitive composition (excluding the weight of a coating solvent). When the compounds capable of decomposing upon irradiation with actinic rays or radiation to generate acids are used in a proportion less than 0.001% by weight, the sensitivity becomes low; while, when the proportion thereof is higher than 40% by weight, the absorption of light by the resulting resist is too great, thereby causing undesirable phenomena, such as deterioration of pattern profile and narrowing of process (particularly bake) margin.
[6] Other Components
The present positive working photosensitive composition can further contain acid-decomposable dissolution inhibiting compounds, dyes, plasticizers, surfactants, spectral sensitizers, organic basic compounds, compounds which can promote the dissolution in a developer, and so on, if needed.
For the present positive working photosensitive composition, it is favorable to contain acid-decomposable dissolution inhibiting compounds. This is because such compounds can increase alkali-solubility discrimination between exposed and unexposed areas to heighten the resolution.
Examples of the acid-decomposable dissolution inhibiting compound include a low molecular weight compound having a molecular weight of 3,000 or below and at least one acid-decomposable group represented by the foregoing formula (X) or (XI) per molecule. In order not to lower the transmittance at wavelengths of 220 nm or below, alicyclic compounds such as the cholic acid derivatives described in Proceeding of SPIE, 2724, 355 (1996), or aliphatic compounds are preferred. When such an acid-decomposable dissolution inhibiting compound is used in the present invention, the proportion thereof is from 3 to 50% by weight, preferably from 5 to 40% by weight, more preferably from 10 to 35% by weight, to the total weight of the photosensitive composition (excluding the weight of a coating solvent).
The compounds capable of promoting the dissolution in a developer are low molecular weight compounds having a molecular weight of 1,000 or below and at least two phenolic OH groups or at least one carboxyl group per molecule. As for the carboxyl group-containing compounds, alicyclic or aliphatic compounds are desirable for the same reason as mentioned above.
It is desirable that such dissolution promoting compounds be added in a proportion of from 2 to 50% by weight, preferably from 5 to 30% by weight, to the resin according to the present invention. If these compounds are added in a proportion greater than 50% by weight, new defects such as deterioration in the development residue and the pattern deformation upon development are caused.
The phenolic compounds having molecular weight of not higher than 1,000 can be prepared with ease with reference to the methods described in, e.g., JP-A-4-122938, JP-A-2-28531, U.S. Pat. No. 4,916,210 and European Patent 0,219,294. ales of such a phenolic compound as mentioned above include the compounds recited below, but these examples are not to be considered as limiting on the scope of compounds usable in the present invention.
Specifically, the phenolic compounds usable in the present invention include resorcin, phloroglucin, 2,3,4-trihydroxybenzophenone, 2,3,4,4xe2x80x2-tetrahydroxybenzophenone, 2,3,4,3xe2x80x2,4xe2x80x2, 5xe2x80x2-hexahydroxybenzophenone, acetone-pyrogallol condensed resins, phloroglucide, 2,4,2,xe2x80x2,4xe2x80x2-biphenyltetrol, 4,4xe2x80x2-thiobis(1,3-dihydroxy)benzene, 2,2,xe2x80x2, 4,4xe2x80x2-tetrahydroxydiphenyl ether, 2,2xe2x80x2,4,4xe2x80x2-tetrahydroxydiphenyl sulfoxide, 2,2xe2x80x2,4,4xe2x80x2-tetrahydroxydiphenyl sulfone, tris (4-hydroxyphenyl)methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4-(xcex1-methylbenzylidene)bisphenol, xcex1,xcex1xe2x80x2,xcex1xe2x80x3-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene, xcex1,xcex1xe2x80x2,xcex1xe2x80x3-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, 1,2,2-tris(hydroxyphenyl)propane, 1,1,2-tris(3,5-dimethyl-4-hydroxyphenyl) propane, 2,2,5,5-tetrakis (4-hydroxyphenyl) hexane, 1,2-tetrakis(4-hydroxyphenyl)ethane, 1,1,3-tris(hydroxyphenyl)butane, para[xcex1,xcex1,xcex1xe2x80x2,xcex1xe2x80x2-tetrakis(4-hydroxyphenyl)]xylene and the like.
The organic basic compounds which can be favorably used in the present invention are compounds having stronger basicity than phenol. Of these compounds, nitrogen-containing basic compounds are preferred.
Preferred examples of the chemical environment thereof include the following structures (A) to (E). 
In formula (A), R250 R251, and R252 may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aminoalkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, provided that R254 and R255 may be bonded to each other to form a ring. 
(In formula (E) R253 R254, R255, and R256 may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms.)
Preferred organic basic compounds are nitrogen-containing basic compounds having, per molecule, two or more nitrogen atoms having different chemical environments. Especially preferred are compounds containing both at least one substituted or unsubstituted amino group and at least one nitrogen-containing ring structure and compounds having at least one alkylamino group. Examples of such preferred compounds include substituted or unsubstituted guanidine, substituted or unsubstituted aminopyridine, substituted or unsubstituted aminoalkylpyridines, substituted or unsubstituted aminopyrrolidine, substituted or unsubstituted indazole, substituted or unsubstituted pyrazole, substituted or unsubstituted pyrazine, substituted or unsubstituted pyrimidine, substituted or unsubstituted purine, substituted or unsubstituted imidazoline, substituted or unsubstituted pyrazoline, substituted or unsubstituted piperazine, substituted or unsubstituted aminomorpholine, and substituted or unsubstituted aminoalkylmorpholines. Preferred substituents include amino, aminoalkyl groups, alkylamino groups, aminoaryl groups, arylamino groups, alkyl groups, alkoxy groups, acyl groups, acyloxy groups, aryl groups, aryloxy groups, nitro, hydroxy, and cyano. Specific examples of especially preferred organic basic compounds include guanidine, 1,1-dimethylguanidine, 1,1,3,3-tetramethylguanidine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2-dimethylaminopyridine, 4-dimethylaminopyridine, 2-diethylaminopyridine, 2-(aminomethyl)pyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-6-methylpyridine, 3-aminoethylpyridine, 4-aminoethylpyridine, 3-aminopyrrolidine, piperazine, N-(2-aminoethyl)piperazine, N-(2-aminoethyl)piperidine, 4-amino-2,2,6,6-tetramethylpiperidine, 4-piperidinopiperidine, 2-iminopiperidine, 1-(2-aminoethyl)pyrrolidine, pyrazole, 3-amino-5-methylpyrazole, 5-amino-3-methyl-1-p-tolylpyrazole, pyrazine, 2-(aminomethyl)-5-methylpyrazine, pyrimidine, 2,4-diaminopyrimidine, 4,6-dihydroxypyrimidine, 2-pyrazoline, 3-pyrazoline, N-aminomorpholine, and N-(2-aminoethyl)morpholine. However, the basic compounds usable in the present invention should not be construed as being limited to the compounds recited above.
Those nitrogen-containing basic compounds can be used alone or as a mixture of two or more thereof. The amount of nitrogen-containing basic compound(s) used is generally from 0.001 to 10 parts by weight, preferably from 0.01 to 5 parts by weight, per 100 parts by weight of the photosensitive composition (excluding a solvent). If the added amount is less than 0.001 parts by weight, any effects to be provided by the addition cannot be exhibited, and if it exceeds 10 parts by weight, there is a tendency of causing the lowering of the sensitivity and deterioration of the developability in unexposed areas.
The suitable dyes are oil dyes and basic dyes. Examples thereof include Oil Yellow #101, Oil Yellow #103, Oil Pink #312, Oil Green BG, Oil Blue BOS, Oil Blue #603, Oil Black BY, Oil Black BS, Oil Black T-505 (all manufactured by Orient Chemical Industries Ltd., Japan), crystal violet (CI 42555), methyl violet (CI 42535), rhodamine B (CI 45170B), malachite green (CI 42000), and methylene blue (CI 52015).
Further, the spectral sensitizers as recited below can be added for the purpose of elevating the rate of acid generation upon exposure. Examples of spectral sensitizers suitable for use in the present invention include benzophenone, p,pxe2x80x2-tetramethyldiaminobenzophenone, p,pxe2x80x2-tetraethylethylamino-benzophenone, 2-chlorothioxanthone, anthrone, 9-ethoxyanthracene, anthracene, pyrene, perylene, phenothiazine, benzil, acridine orange, benzoflavin, cetoflavin T, 9,10-diphenylanthracene, 9-fluorenone, acetophenone, phenanthrene, 2-nitrofluorene, 5-nitroacenaphthene, benzoquinone, 2-chloro-4-nitroaniline, N-acetyl-p-nitroaniline, p-nitroaniline, N-acetyl-4-nitro-1-naphthylamine, picramide, anthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-1,9-benzanthrone, dibenzalacetone, 1,2-naphthoquinone, 3,3xe2x80x2-carbonylbis(5,7-dimethoxycarbonylcoumarin), and coronene. However, the spectral sensitizers usable in the present invention should not be construed as being limited to these examples.
In addition, those spectral sensitizers can be used as an absorbent for far ultraviolet rays of a light source. Such absorbents can reduce the reflected light from a substrate to lessen the influence of multiple reflection inside the resist film; as a result, an effect on standing wave improvement can be produced.
All the ingredients as mentioned above are dissolved in a solvent to prepare the present photosensitive composition, and applied to a support. Examples of the solvent used therein include ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, xcex3-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethylacetate, ethylene glycol monoethylether acetate, propylene glycol monomethyl ether, propylene glycol monomethylether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, N,N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone and tetrahydrofuran. These solvents are used alone or as a mixture of two or more thereof.
Also, a surfactant can be added to the solvent as recited above. Examples of such a surfactant include nonionic surfactants, such as polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether), polyoxyethylene alkyl aryl ethers (e.g., polyoxyethylene octyl phenol ether, polyoxyethylene nonyl phenol ether), polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acid esters (e.g., sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate) and polyoxyethylenesorbitan fatty acid esters (e.g., polyoxyethylenesorbitan monolaurate, polyoxyethylenesorbitan monopalmitate, polyoxyethylenesorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylenesorbitan tristearate); fluorine-containing surfactants, such as Eftop EF301, EF303 and EF352 (commercial names, products of Shin-Akita Kasei K. K.), Megafac F171 and F173 (commercial names, products of Dai-Nippon Ink and Chemicals, Inc.), Florade FC430 and FC431 (commercial names, products of Sumitomo 3M Co., Ltd.), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105 and SC106 (commercial names, products of Asahi Glass Company, Ltd.); organosiloxane polymers, such as KP341 (produced by Shin-Etsu Chemical Co., Ltd.); and acrylic or methacrylic acid (co)polymers, such as Polyflow No. 75 and No. 95 (commercial names, products of Kyoeisha Yushi Kagaku Kogyo K. K.). The amount of those surfactants added is generally not greater than 2 parts by weight, preferably not greater than 1 parts by weight, per 100 parts by weight of the total solids in the composition.
Those surfactants may be added alone or as a mixture of two or more thereof.
The aforementioned photosensitive composition is coated on a substrate (e.g., silicon/silicon dioxide coating) as employed for the production of precise integrated circuit elements by the use of an appropriate coating means, e.g., a spinner and a coater, exposed to light via a desired mask, baked and then developed to provide a satisfactory resist pattern. Herein, it is desirable that the light used for the exposure be far ultraviolet rays having wavelengths of 250 nm or shorter, preferably 220 nm or shorter. More specifically, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F2 excimer laser (157 nm), X-ray and electron beams can be employed.
The developer usable for the photosensitive composition of the present invention is an alkaline aqueous solution containing an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate or aqueous ammonia, a primary amine such as ethylamine or n-propylamine, a secondary amine such as diethylamine or di-n-butylamine, a tertiary amine such as triethylamine or methyldiethylamine, an alcohol amine such as dimethylethanolamine or triethanolamine, a quaternary ammonium salt such as tetramethylammonium hydroxide or tetraethylammonium hydroxide, or a cyclic amine such as pyrrole or piperidine.
To such an alkaline aqueous solution, an alcohol and a surfactant can be added in appropriate amounts.